This invention is directed to a voltage detection integrated circuit, and in particular to a voltage detection circuit that is fully adjustable as a result of an adjustment circuit that is integrated into the same circuit chip as the remaining circuits comprising the voltage detection circuit.
Heretofore, voltage detection circuits of the type known in the art have compared a voltage produced by a voltage source with a set voltage and produced a comparison signal representative thereof. Accordingly, the detecting voltage, or set voltage, is varied by utilizing an adjustment element such as a variable resistor or, alternatively, by replacing or changing the resistors in the circuit. Although the latter approach is permissible when the voltage detection circuit is not an integrated circuit, when the voltage detection circuit is integrated into a circuit chip, it is necessary to provide a variable resistor that is mechanically coupled to the voltage detection circuit and must be manually adjusted in order to permit either the set voltage or the voltage to be detected to be varied.
This type of manual adjustment is extremely difficult to effect and the finer the adjustment required, the more costly it becomes. Moreover, regulation of the voltage detection circuit is often necessitated by fluctuations in the electrical characteristics of passive and active elements utilized, not only in the voltage detection circuit, but in the circuitry that the electronic detection circuit is coupled to. Thus, in comparison to the considerable cost savings that obtains when a voltage detection circuit and, additionally, the circuitry in which same is included are integrated into the same circuit chip, adjustment of the voltage detection circuitry by manually varying an impedance element is time consuming, extremely costly and is a less completely satisfactory method of adjusting the operating characteristics of an integrated voltage detection circuit.